Effect of NickeleZinc Co-doped TiO 2 blocking layer on performance of DSSCs T.S. Bramhankar a , S.S. Pawar b, * , J.S. Shaikh c , V.C. Gunge a , N.I. Beedri d , P.K. Baviskar d , H.M. Pathan d , P.S. Patil c , R.C. Kambale d , R.S. Pawar d a Department of Mechanical Engineering, Sinhgad College of Engineering, Vadgaon, Pune, 41, India b Department of Engineering Sciences, Sinhgad College of Engineering, Vadgaon, Pune, 41, India c Department of Physics, Shivaji University, Kolhapur, 04, India d Department of Physics, Savitribai Phule Pune University, Pune, 411007, India article info Article history: Received 14 August 2019 Received in revised form 22 October 2019 Accepted 25 October 2019 Available online xxx Keywords: Ni-Zn co-doped TiO 2 Blocking layer Mercurochrome dye Impedance spectroscopy Dye sensitized solar cell abstract Photovoltaic parameters in Dye-sensitized solar cells (DSSCs) are improved through the employment of Ni and Zn co-doped TiO 2 thin film as a Photo-anode material in DSSCs. The TiO 2 layers having different ratio of Ni and Zn were deposited over fluorine doped tin oxide (FTO) substrate using the spin coating technique. Organic dyes like mercurochrome (MC) dye were emerged out to use as sensitizer with TiO 2 photoanode based DSSCs. The optical property of bare TiO 2 , NZT-20, NZT-40, NZT-60 and NZT-80 blocking layer prepared by using Ni and Zn-doped TiO 2 with different doping concentrations were studied. The values of the bandgap were found to be 3.83, 3.78, 3.82 and 3.83 eV for TiO 2 doped with Ni and Zn concentrations such as NZT-20, NZT-40, NZT-60 and NZT-80 respectively. Electrochemical impedance spectroscopy (EIS) was used to study the charge transfer resistance and interfacial capaci- tances that are present in a DSSCs. The EIS measurements are used to calculate values of charge transfer capacitance and resistance of all samples. The NZT-80 sample has a high value of resistance and capacitance so that it affects the photovoltaic performance of DSSC. The Blocking layer incorporated in NZT-80 sample gives 61% increased in the efficiency as compared to its bare TiO 2 (without Co-doped Ni eZn) photoanode. © 2019 Elsevier B.V. All rights reserved. 1. Introduction Nowadays, human beings are facing a problem of an energy crisis, because of rising global energy demand coupled with increasingly high oil prices. Solar energy has the potential to overcome these problems [1]. Solar energy is a source of renewable energy which provides radiant light and heat energy to the living beings of the planet Earth. It is used in different forms of applica- tions like solar heating, photovoltaic, solar thermal energy, solar architecture etc. Out of these, the use of photovoltaic systems is one of the best promising solar energy harnessing techniques [2]. DSSCs are photovoltaic solar cells, belonging to the third generation of solar cells were discovered by Gratzel and O’Regan in 1991 [3]. They are based on Nature’s principles of photosynthesis. DSSCs are composed of a porous layer of titanium dioxide nano-particles called as a photoanode, covered with a molecular dye that ab- sorbs sunlight very similar to the chlorophyll in green leaves [4]. The semiconductor photoanode of DSSC immediately determine the photocurrent density as it not only moving of photoinduced electrons towards load but also adsorbs dyes molecules [3e6]. Semiconductor photo-anode plays a major role in the working process of DSSC. The metal oxide materials are generally used for making photo-anodes because of large surface area and highly porous structure which helps for dye adsorption into semi- conductor material [3,5,6]. An ideal DSSC photo-anode material should provide a large surface for dye loading and transfer the photo-generated electrons from dye to external circuit effectively so that, its band edge should match with the band gap structure of the dye for efficient injection of electrons. Normally, this requires the conduction band of semiconductor 0.2e0.3 eV lower than that of the sensitizer [7 ,8]. Based on these criteria, nano-structured semiconductor materials such as titanium dioxide (TiO 2 )[9, 10], zinc oxide (ZnO) [11 , 12], tin oxide (SnO 2 )[13, 14], zirconia (ZrO 2 ) * Corresponding author. E-mail address: sspawar.phy@gmail.com (S.S. Pawar). Contents lists available at ScienceDirect Journal of Alloys and Compounds journal homepage: http://www.elsevier.com/locate/jalcom https://doi.org/10.1016/j.jallcom.2019.152810 0925-8388/© 2019 Elsevier B.V. All rights reserved. Journal of Alloys and Compounds xxx (xxxx) xxx Please cite this article as: T.S. Bramhankar et al., Effect of NickeleZinc Co-doped TiO 2 blocking layer on performance of DSSCs, Journal of Alloys and Compounds, https://doi.org/10.1016/j.jallcom.2019.152810